Definitions of Digestive Terms

A

Area between the chest and the hips that contains the stomach, small intestine, large intestine, liver, gall bladder, pancreas, and spleen.

Absorption

The process by which nutrients move from the intestines, mostly into the bloodstream, to nourish the body.

Adaptive response

A helpful, protective response.

Aerophagia

Ingestion of air.

Afferent nerves

Nerve fibers (usually sensory) that carry impulses from an organ or tissue toward the brain and spinal cord (central nervous system), or the information processing centers of the enteric nervous system, which is located within the walls of the digestive tract.

Afferent pathways

Nerve structures through which impulses are conducted from a peripheral part (e.g., the gut or intestines) toward a nerve center (e.g., the central nervous system).

Aganglionosis

Absence of nerve cells.

Algorithm

A step-by-step protocol for management of a health care problem.

Allodynia

Pain due to stimuli that do not normally provoke pain.

Allostasis

The ability of the organism to achieve stability through adaptation or change. This process, which is critical to our survival, involves the autonomic nervous system, the HPA axis, and the cardiovascular, metabolic, and immune systems which act to protect the body by responding to internal and external stimuli. Paradoxically, these same systems, when activated by stress, can protect and restore as well as damage the body.

Ambulatory care

Health services provided in a doctor's office, or on an outpatient basis.

Amino Acids

A group of 20 different kinds of small molecules that link together in long chains to form proteins. Often referred to as the "building blocks" of proteins.

Anal canal

The lowermost portion of the large intestine.

Anal fissure

Crack in the skin in or adjacent to the anal canal.

Anal incontinence

Any leakage of liquid or solid stool or excessive leakage of gas.

Analgesic

Pain relieving.

Anastomosis, intestinal

Reattachment of two portions of bowel.

Anismus

A condition marked by the failure of pelvic floor muscles to relax, or a paradoxical contraction of the pelvic floor muscles, with defecation. Also referred to as pelvic floor dyssynergia.

Anorexia

Loss of appetite.

Antigen

A substance or molecule recognized by the immune system, such as bacteria or a virus.

Antinociception

Increased tolerance to pain.

Antispasmodics

Drugs that inhibit smooth muscle contraction in the gastrointestinal tract.

Anorectal manometry

A test that can be used to measure resting and squeezing anal sphincter pressures, rectal sensation and compliance, and sphincter response.

Anus

The opening of the rectum.

Autonomic

Involuntary.

Autonomic nervous system

The part of the nervous system that controls involuntary actions of internal organs such as the bowel.

B

Bacteria

Very small organisms (microbes) that are normally in the gut (intestines). There are over 500 different kinds known to live in the gut; most (up to several billion) bacteria are in the large intestine (colon). "Normal" bacteria have important functions in life and health. Bacteria that can cause infection are called "pathogens." Normal bacteria protect against pathogens.

Barium

A metallic, chemical, chalky, liquid used to coat the inside of organs so that they will show up on an x-ray.

Basic science

The fundamental approach to understanding how systems work. Basic research takes place in the laboratory and often involves the study of molecules and cells.

Bile

Secretions of the liver that aid in digestion and absorption of nutrients in the intestinal tract.

Bifidobacterium infantis 35624

A type of bacteria that, in the right amount, may have a beneficial effect (probiotic), and help lessen some bowel symptoms.

Biliary tract

Gall bladder and the bile ducts.

Biologics

Biological organisms grown in labs. They are meant to treat, prevent, or diagnose medical conditions or diseases.

Biofeedback therapy

A painless neuromuscular reeducation tool in which a therapist, using special sensors to monitor functions that we are usually not aware of, helps to change abnormal functions to more normal and effective functions.

Biomedical model

The model of illness and disease in Western medical education and research. It has two assumptions: (1) reductionism - that all conditions can be linearly reduced to a single cause, and (2) dualism - where illness and disease are divided either to an "organic" disorder having an objectively defined cause, or a "functional" disorder, with no specific cause or pathophysiology. The biomedical model is not sufficient to explain the functional GI disorders.[Rome II]

Biopsy

Tissue sample.

Biopsychosocial model

A model that proposes that illness and disease result from simultaneously interacting systems at the cellular, tissue, organismal, interpersonal, and environmental level. It incorporates the biologic aspects of the disorder with the unique psychosocial features of the individual, and helps explain the variability in symptom expression among individuals having the same biologic condition.

Blinding

A process in a clinical study that conceals a treatment from the patient.

Borborygmi

Audible rumbling abdominal sounds due to gas gurgling with liquid as it passes through the intestines.

Bowel

The intestines.

Bowel control

Ability to delay defecation or passing of intestinal gas in a controlled manner.

Bowel incontinence

Inability to delay defecation in a controlled manner.

Bowel management or retraining

A program to help develop a more predictable schedule for elimination and decrease unpredictable episodes of incontinence. It may involve normalizing stool consistency, usually through dietary changes; establishing a regular time for elimination; and stimulating emptying on a regular basis.

Brain-gut axis

The continuous bi-directional flow of information and feedback that takes place between the gastrointestinal tract, and the brain and spinal cord (which together comprise the central nervous system).

C

A retrospective study that compares patients who already have a disease or outcome of interest (cases) with patients who do not have the disease or outcome (controls).

Case series

A report about a small group of similar patients with a disease, or outcome of interest before and after an intervention with no control group.

Celiac disease

Inability to digest and absorb the protein gliadin (a component of gluten). Gliadin is found in wheat, rye, barley, and oats. Celiac disease is also called celiac sprue, and gluten intolerance.

Cell

The basic unit of any living organism. It is a small, watery, compartment filled with chemicals and a complete copy of the organism's genome.

Central amplification

Changes that occur in the central nervous system (brain and spinal cord) that affect cell transmitters and receptors, thereby increasing the excitability of neurons and resulting in heightened perception of signals from the gastrointestinal tract.

Cholecystectomy

Surgical removal of the gallbladder.

Chronic

Symptoms occurring over a long period of time.

Chronic intestinal pseudo-obstruction (CIP)

A rare disorder of gastrointestinal motility where coordinated contractions (peristalsis) in the intestinal tract become altered and inefficient.

Clinical science

The approach aimed at understanding the diagnosis and treatment of diseases and disorders through studies involving people, usually carried out in clinical settings.

Clinical significance

A conclusion that an intervention has an effect that is of practical meaning to patients and health care providers.

Clinical trial

An experimental research study that tests new medical interventions on people. These interventions may include drugs, devices, or other instruments.

Clostridium difficile (C. difficile)

A gram-positive anaerobic bacterium. C. difficile is recognized as the major causative agent of colitis (inflammation of the colon) and diarrhea that may occur following antibiotic intake.

Cohort

A group that shares the same characteristics among its members.

Cohort study

An observational study in which outcomes in a group of patients that received an intervention are compared with outcomes in a similar group (the cohort) either contemporary or historical, of patients that did not receive the intervention.

Colectomy

Removal of part or all of the colon.

Colitis

Inflammation of the colon.

Colon

The large intestine.

Colonic inertia

Delayed colonic action. Symptoms include long delays in the passage of stool accompanied by lack of urgency to move the bowels

Colonoscopy

Colonoscopy is a fiberoptic (endoscopic) procedure in which a thin, flexible, lighted viewing tube (a colonoscope) is threaded up through the rectum for the purpose of inspecting the entire colon and rectum and, if there is an abnormality, taking a tissue sample of it (biopsy) for examination under a microscope, or removing it.

Colostomy

A surgically created opening of the colon to the abdominal wall, allowing the diversion of fecal waste.

Commensals

Non-pathogenic microorganisms that become part of the host's normal flora.

Thoughts and behaviors that people use to gain control of, tolerate, reduce, or minimize stressful events.

Corticotropin-releasing factor (CRF)

CRF is a family of peptides. They act as messengers and interact with CRF receptors on cells (CRF1 and CRF2) that receive a stimulus or message, which induce a physiological response in the body. These CRF peptides and receptors are located, among other sites, both in the brain and the gut in regions linked with digestive function, emotional behavior, and autonomic nervous system activity.

Cortisol

A hormone associated with the physical effects of the stress response within the body.

Crohn's disease

A chronic form of inflammatory bowel disease.

Cross-sectional study

A study that measures the prevalence of health outcomes and/or determinants of health in a population at a point in time or over a short period of time.

Cyclic vomiting syndrome (CVS)

A disorder with recurrent episodes of severe nausea and vomiting interspersed with symptom free periods.

Cytokines

A type of protein released by cells of the immune system, which act through specific cell receptors to regulate immune responses.

D

Declaration of Helsinki

A set of guidelines adopted in Helsinki, Finland, in 1964. The Declaration addressed the ethics of clinical research and recommended specific safeguards, including informed consent.

Defecography

A test that uses x-rays to look at the behavior of the rectum and anus during attempts to defecate.

Dehydration

An excessive loss of fluids in the body.

Diabetes

A disease in which blood glucose (blood sugar) levels are above normal. Type 2 diabetes, also known as adult-onset or noninsulin-dependent diabetes mellitus (NIDDM), is the most common form of diabetes.

Diaphragm

The muscle wall between the chest and the abdomen.

Diarrhea

Passing frequent and/or loose or watery stools. Acute diarrhea goes away in a few weeks, and becomes chronic when it lasts longer than 4 weeks.

Digestion

The process by which food is converted into substances that can be absorbed and assimilated by the body.

Digestive tract

A group of hollow organs that forms a long, twisting tube extending from the mouth to the anus through which food is ingested, digested, and expelled.

Digital examination

Physical exam in which the doctor inserts his or her finger.

Dilatation

Expansion of an organ or vessel.

Discomfort

An unpleasant, but not painful, feeling.

Disease

A condition of an organic being or of one of its parts that impairs normal living functioning.

Disorder

A disturbance in regular or normal function. An abnormal condition.

Distal esophageal spasm (DES)

A rare motility (movement) disorder of the lower (distal) two-thirds of the esophagus. Occurring equally in men and women, the most common symptoms are chest pain and difficulty swallowing. Some patients may experience unusual symptoms like an unexplained cough.

Distention

An uncomfortable swelling in the intestines.

Diverticula

Small pouches in the colon.

Diverticulitis

Occurs when diverticula become infected or irritated.

Diverticulosis

A condition of having multiple diverticulum in the walls of the colon. Also called uncomplicated diverticular disease.

Diverticulum

Singular of diverticula.

DNA

Abbreviation for deoxyribonucleic acid, the molecule that contains the genetic code for all life forms (except for a few viruses).

Domperidone

A pro-motility agent, domperidone, has been used in countries outside of the U.S. to treat gastroparesis or severe GI motility disorders. In 2004 the FDA determined that there are some patients with severe gastrointestinal disorders that are refractory (resistant) to standard therapy, who may benefit from domperidone and in whom the drug's benefits outweigh its risks. FDA encourages physicians who would like to prescribe domperidone for their patients with severe gastrointestinal disorders that are refractory to standard therapy to open an Investigational New Drug Application (IND). Find out more at this FDA web page.

Double blinding

A process in a clinical study that conceals the treatment from both the patient and the investigator.

Dumping syndrome

A collection of symptoms that occurs when food is emptied too quickly from the stomach.

Duodenum

The first part of the small intestine.

Dysbiosis

A disturbance or imbalance in a biological system, for example, changes in the types and numbers of bacteria in the gut which may lead to developing different diseases.

Dysmotility (intestinal)

Abnormal contractions, of varying frequency and severity, of the muscles in the gastrointestinal tract, which may or may not be associated with symptoms. They differ from functional gastrointestinal disorders, which are defined by symptoms that may or may not have dysmotility, but which are also associated with low pain thresholds (visceral hypersensitivity). When occurring in the stomach or small intestine, dysmotility can result in disorders like gastroparesis or with or without symptoms such as bloating, pain, nausea, and vomiting due to either disorganized contractions, or weak contractions. When occurring in the large intestine, dysmotility can result in disorders like Hirschsprung's disease or colonic inertia that can produce symptoms of constipation, or other conditions that cause diarrhea. The abnormal motility involves changes in the contractions that either move or hold back stool. Abnormalities of "dysmotility" can be measured with special motility testing.

Dyspepsia

A term often used to describe pain or discomfort that occurs in the upper abdominal area.

A procedure that uses an endoscope to diagnose or treat a condition. There are many types of endoscopy; examples include colonoscopy, sigmoidoscopy, gastroscopy, enteroscopy, and esophogealgastroduodenoscopy (EGD).

Enteral nutrition

Food provided through a tube placed in the nose, stomach, or small intestine.

Enteric nervous system (ENS)

Autonomic nervous system within the walls of the digestive tract. The ENS regulates digestion and the muscle contractions that eliminate solid waste.

Enteritis

An irritation of the small intestine.

Enterocele

The descent of loops of small intestine into the pelvis, that bulge into the vagina during straining. An enterocele may cause pain and/or obstructed defecation.

Enterocolitis

Inflammation of the intestines.

Enteroids

Intestinal tissue models used in pre-clinical research, ex vivo.

Enteroscopy

Examination of the inside of the small intestine using an endoscope.

Eosinophilic gastroenteritis

A rare disease characterized by food-related reactions, infiltration of certain white blood cells (eosinophils) in the GI tract, and an increase in the number of eosinophils in the blood.

Epidemiology

The study of the distribution of health-related states or events in specified populations and the application of this study to the control of health problems.

Episiotomy

An incision made in the skin between the vagina and anus meant to enlarge the vaginal opening during childbirth in order to prevent tearing and to facilitate delivery of an infant.

Epithelium

The inner and outer tissue covering digestive tract organs.

ERCP (endoscopic retrograde cholangiopancreatography)

A procedure for the examination or treatment of the bile ducts (biliary tree) and pancreatic ducts that combines the use of x-rays and an endoscope. Used to diagnose and manage problems of the liver, gallbladder, bile ducts, and pancreas such as gallstones and their complications, pancreatic and biliary cancers, pancreatitis and its complications, and pancreaticobiliary pain. The procedure carries a risk of serious complications, requires conscious sedation of the patient, and is performed by gastroenterologists or other physicians with special training.

Esophagitis

Inflammation of the esophagus.

Esophagus

The organ that connects the mouth to the stomach.

Esophogealgastroduodenoscopy (EGD)

Examination of the inside of the esophagus, stomach, and duodenum using an endoscope. (Also called Upper Endoscopy)

Etiology

Cause.

Etiologic mechanisms

The processes that cause or contribute to the cause of diseases or conditions.

Evidence-based

Findings based on the use of current best evidence from scientific and medical research.

Evidence-based medicine

The conscientious, explicit and judicious use of the current best evidence from clinical care research in making decisions about the care of individual patients

Extraintestinal

Occurring outside the intestines.

Ex vivo

The process where living cells, tissues, or organs are cultured outside of a living organism for treatment or analysis under controlled conditions.

A disorder of gut-brain interaction. A functional disorder has its basis in how a bodily system works. A functional GI disorder refers to a "disorder of functioning" where the body's normal activities in terms of the movement of the intestines, the sensitivity of the nerves of the intestines, or the way in which the brain controls some of these functions is impaired. However, there are no structural abnormalities that can be seen by endoscopy, x-ray, or blood tests. Thus a functional GI disorder is identified by the characteristics of the symptoms

H

The impact an illness has on quality of life, including the individual's perception of his or her illness.

Health-related quality of life (HRQL) measures

Patient outcome measures that extend beyond traditional measures of mortality and morbidity, to include such dimensions as physiology, function, social activity, cognition, emotion, sleep and rest, energy and vitality, health perception, and general life satisfaction. (Some of these are also known as health status, functional status, or quality of life measures.)

Helicobacter pylori (H. pylori)

A bacterium that can damage stomach and duodenal tissue, causing ulcers.

Hemorrhoids

Veins around the anus or lower rectum that are swollen and inflamed.

Hepatic

Related to the liver.

Heredity

The passing of a trait from parent to offspring through genetically coded information

Hereditary

Genetically transmitted or transmittable from parent to offspring.

Heritability

The extent to which a trait is influenced by our genetic makeup.

Hiatal hernia

A small opening in the diaphragm that allows the upper part of the stomach to move up into the chest.

Hirschsprung's disease

A rare disorder present at birth (congenital) that is caused by absence of nerve cells (ganglion) in the rectum and/or colon.

Homeostasis

Maintenance of a relatively stable or balanced internal body state despite environmental fluctuations. The tendency in an organism toward maintenance of physiological and psychological stability.

Hormones

Chemical messengers in the body, which travel in the bloodstream to tissue and organs affecting different processes.

HPA (hypothalamic-pituitary-adrenal) axis

A system within the body that responds to stress by stimulating or inhibiting the release of various hormones, in particular cortisol, into the blood which then stimulates systems essential to self-preservation.

Hyperalgesia

Lowered threshold (higher sensitivity) to pain.

Hypersensitivity

An increased or amplified response to stimuli.

Hypervigilance

Increased vigilance. An intensified state of paying attention to or focusing on specific things. May severely limit a person's ability to focus on specific tasks or engage in reflective thinking when their focus is on scanning for threatening stimuli. A person with a functional GI disorder or incontinence may be hypervigilant when their focus is on scanning for bodily sensations or indications that signal symptom onset.

I

A surgically created opening of the abdominal wall to the ileum, allowing the diversion of fecal waste.

Ileum

The lower third of the small intestine, adjoining the colon.

Illness

The patient's experience of feeling unwell that may include impairment of normal physiological and social function.

Imaging

Tests that produce pictures of areas inside the body.

Imperforate anus

A birth defect in which the anal canal fails to develop, treated surgically.

Incidence

Describes the occurrence of a disease or disorder in a population. It is a rate, showing how many new cases of a disease occurred in a population (typically a susceptible population called the "at-risk population" ) during a specified interval of time (usually expressed as number of new cases per unit time per fixed number of people; e.g., number of new cases per 1,000 persons in one year).

Inflammation

Redness, swelling, pain, and/or a feeling of heat in an area of the body. This is a protective reaction to injury, disease, or irritation of the tissues.

Inflammatory bowel disease (IBD)

Long-lasting problems that cause irritation and ulcers in the gastrointestinal tract. The most common disorders are ulcerative colitis and Crohn's disease.

Ingestion

Taking into the body by mouth.

Inherited

Transmitted through genes from parents to offspring.

Innervated

A structure supplied with intact nerves.

Institutional review board (IRB)

In the U.S. a group of scientists, doctors, clergy, and consumers at each health care facility that participates in a clinical trial. IRBs are designed to protect study participants. They review and must approve the action plan for every clinical trial. They check to see that the trial is well designed, does not involve undue risks, and includes safeguards for patients.

Interstitial cells of Cajal (ICC)

Specialized cells found throughout the gastrointestinal tract that are required for normal gastrointestinal motility.

Interstitial cystitis

A long-lasting condition also known as painful bladder syndrome or frequency-urgency-dysuria syndrome. The wall of the bladder becomes inflamed or irritated, which affects the amount of urine the bladder can hold and causes scarring, stiffening, and bleeding in the bladder.

The ability to control uptake across the mucosa and protect from damage of harmful substances from the lumen.

Intestinal mucosa

The surface lining of the intestines where the cells absorb nutrients.

Intestinal permeability

The barrier properties of the lining of the intestines, which prevent harmful substances from passing through into the body.

Intestinal pseudo-obstruction

A motility disorder with symptoms like those of a bowel blockage, but with no physical evidence of blockage or obstruction. Symptoms may include cramps, stomach pain, nausea, vomiting, bloating, fewer bowel movements than usual, and loose stools.

Intestinal stenosis

A partial obstruction that narrows the opening in the intestine.

Intestines

Also known as the gut or bowels, is the long, tube-like organ in the human body that completes digestion or the breaking down of food. They consist of the small intestine and the large intestine.

Intractable

Symptoms that don't respond to usual treatments.

Investigational

In U.S. clinical trials, refers to a drug (including a new drug, dose, combination, or route of administration) or procedure that has undergone basic laboratory testing and received approval from the Food and Drug Administration (FDA) to be tested in human subjects. A drug or procedure may be approved by the FDA for use in one disease or condition, but be considered investigational in other diseases or conditions. Also called experimental.

Investigational New Drug Application (IND)

A petition to the FDA to allow testing of a new drug in clinical trials.

In vitro

In the laboratory (outside the body). The opposite of in vivo (in the body).

In vivo

In the body. The opposite of in vitro (outside the body or in the laboratory).

Irritable bowel syndrome (IBS)

A functional bowel disorder in which abdominal discomfort or pain is associated with a range of symptoms. Typically, these include intermittent abdominal pain accompanied by diarrhea, constipation, or alternating episodes of both.

Ischemic colitis

Inflammation of the large intestine (colon) caused by decreased blood flow to the colon. Symptoms may include: abdominal pain, fever, vomiting, blood in the stool, diarrhea, low back pain.

J

L

Laboratory study

Research done in a laboratory. These studies may use test tubes or animals to find out if a drug, procedure, or treatment is likely to be useful. Laboratory studies take place before any testing is done in humans.

Laboratory test

A medical procedure that involves testing a sample of blood, urine, or other substance from the body. Tests can help determine a diagnosis, plan treatment, check to see if treatment is working, or monitor the disease over time.

Lactose

A sugar found commonly in milk and dairy products.

Lactose intolerance

The inability to digest or absorb lactose.

Laparoscopy

The insertion of a thin, lighted tube (called a laparoscope) through the abdominal wall to inspect the inside of the abdomen and remove tissue samples.

Large intestine

The long, tube-like organ that is connected to the small intestine at one end and the anus at the other. The large intestine has four parts: cecum, colon, rectum, and anal canal. Partly digested food moves through the cecum into the colon, where water and some nutrients and electrolytes are removed. The remaining material, solid waste called stool, moves through the colon, is stored in the rectum, and leaves the body through the anal canal and anus.

Laxative

A compound that increases fecal water content.

Limbic system

A network of brain regions involved in the regulation of the function of internal organs, emotions, and the maintenance of homeostasis.

Lumen

The cavity of a tubular organ, such as the intestines.

Lymphocyte

A type of white blood cell. Lymphocytes have a number of roles in the immune system, including the production of antibodies and other substances that fight infection and diseases.

M

A test that uses a magnet and radio waves to generate signals from inside the body used to construct images of internal structures.

Malabsorption

Difficulty absorbing nutrients from food

Maldaptive response

An unhelpful or detrimental response.

Malnutrition

The condition that occurs when the body does not get enough nutrients.

Manometry

A test that measures pressure or contractions in the intestinal tract.

Mast cell

A type of immune system cell present in blood and tissue.

Mast cell degranulation

The release from within the cell of granules, or small sacs, containing chemicals that can digest microorganisms and activate other cells to fight infection.

Mediators

Substances within the body, such as hormones, that can transmit messages to nerve or muscle tissue to stimulate a response.

Meta-analyses

A method of summarizing previous research by reviewing and combining results from multiple studies.

Metabolism

The biochemical process the body uses to make energy from what we eat and drink.

Metabolites

Substances produced by cells as they break down larger molecules and produce energy.

Microbial metabolites

Substances produced by our gut microbes by fermenting food components that the human intestine cannot process or absorb.

Microbiome

A collection of different microbes and their functions or genes found in an environmental habitat. Different parts of the body have different microbiomes, for example, the skin microbiome is different to the gut microbiome, but they are all part of the human microbiome.

Microbiota

The collective community of microorganisms, or microbes, such has bacteria or viruses, that live on or within different parts of our bodies, like the skin, mouth, and the gut.

Migration

The movement of cells, etc. from one position to another.

Mitochondria

Structures within cells that convert the energy from food into a form that cells can use.

Mitochondrial DNA

DNA, or genetic material, within mitochondria.

Morbidity

A disease or the incidence of disease within a population. Morbidity also refers to adverse effects caused by a treatment.

Motility

Spontaneous movement. A term used to describe the motor activity of smooth muscles in the gastrointestinal (GI) tract

MRI

Magnetic resonance imaging.

Mucosa

A mucous membrane that lines body passageways and cavities such as the esophagus, stomach, and intestines.

N

A description of what happens to a medical condition over time (e.g., improves, stays the same, worsens) in the absence of treatment.

Nasograstro tube (NG-tube)

A method of enteral feeding in which a tube is placed through a nasal passageway into the stomach.

Nerve(s)

Cells in the human body that are the building blocks of the nervous system (the system that records and transmits information chemically and electrically within a person). Nerve cells, or neurons, are made up of a nerve cell body and various extensions from the cell body that receive and transmit impulses from and to other nerves and muscles.

Neural

Having to do with nerves or the nervous system, including the brain and the spinal cord.

Neurons

Nerve cells.

Neuroendocrinology

The science of how hormones and glands interact with the nervous system.

Neurological

Having to do with nerves or the nervous system.

Neuronoal intestinal dysplasia (NID)

A variety of conditions in which nerve cells (ganglion) are present in the colon but may be abnormal in their position, number, maturity, or appearance.

Neuropeptide

A member of a class of protein-like molecules made in the brain used by neurons to communicate with each other.

Neurotransmitter

A chemical in the nervous system that helps transmit messages.

NIDDK or National Institute of Diabetes and Digestive and Kidney Diseases

One of the 27 NIH Institutes and Centers, the NIDDK conducts and supports basic and applied research and provides leadership for a national program in diabetes, endocrinology, and metabolic diseases; digestive diseases and nutrition; and kidney, urologic, and hematologic diseases. Access the NIDDK web site at http://www.niddk.nih.gov.

NIH or National Institutes of Health

The focal point of biomedical research in the United States. NIH conducts research in its own laboratories; supports the research of non-Federal scientists in universities, medical schools, hospitals, and research institutions throughout the country and abroad; helps in the training of research investigators; and fosters communication of medical information. Access the NIH web site at http://www.nih.gov.

Nonblinded

Describes a clinical trial or other experiment in which the researchers know what treatments are being given to each study subject or experimental group. If human subjects are involved, they know what treatments they are receiving.

Noxious stimulus

Stimulus that causes or has the potential to cause pain.

Nutrient

A chemical compound (such as protein, fat, carbohydrate, vitamins, or minerals) that make up foods.

Nutrition

The taking in and use of food and other nourishing material by the body.

P

P value

The p (probability) value is a calculation used in studies to determine if the results are caused by chance or not. The lower the p-value, the more likely it is that the difference between groups was caused by treatment. A p value less than 0.05 is statistically significant and indicates that the result is not due to chance.

Pain threshold

The point at which a person becomes aware of pain.

Palpation

Examination by pressing on the surface of the body to feel the organs or tissues underneath.

Parenteral nutrition

The slow infusion of a solution of nutrients into a vein through a catheter, which is surgically implanted. This may be partial, to supplement food and nutrient intake, or total (TPN, total parenteral nutrition), providing the sole source of energy and nutrient intake for the patient.

Pathogenesis

The origin and development of a disease or disorder.

Pathogens

Disease causing microorganisms.

Pathological

Disease related.

Pathology

The study of the fundamental nature, causes, and development of abnormal conditions and the structural and functional changes that result.

Pathophysiologic mechanisms

Processes involved with a particular function.

Pathophysiology

Changes or alterations in function that accompany a particular syndrome or disease, generally as distinguished from structural defects.

Pelvic

Having to do with the pelvis (the lower part of the abdomen located between the hip bones).

Pelvic floor

A group of muscles that support the pelvic organs, participate in defecation, and help maintain continence.

Pelvic floor dyssynergia

A problem with the way certain nerves and muscles function in the pelvic floor.

Peptic ulcer

A sore in the lining of the esophagus, stomach, or duodenum, usually caused by the bacterium Helicobacter pylori (H. pylori). An ulcer in the stomach is a gastric ulcer; an ulcer in the duodenum is a duodenal ulcer.

Perineum

The area of the body between the anus and the vulva in females, and between the anus and the scrotum in males.

Peristalsis

Synchronized or coordinated contraction of the muscles that propel food content through the gastrointestinal (GI) tract to facilitate normal digestion and the absorption of nutrients. Peristalsis is dependent upon the coordination between the muscles, nerves, and hormones in the digestive tract.

Pharmacogenomics

The study of how genes affect a person's response to drugs.

Pharmacokinetics

How the body handles a drug, including how it is absorbed, circulated, transformed, and eliminated.

Physiology

The study of how the body functions at the levels of organs, cells, and molecules.

Pilot study

The initial study examining a new method or treatment.

Placebo

A placebo is an effect, not merely a thing. It is more or less a component of all healing yet is poorly understood or studied. In clinical trials a placebo pill, device, or procedure acts as a control to ensure that the effect seen with the treatment is specific, not only the result of the placebo effect or the natural evolution of an illness that accompany every therapeutic encounter. (Thompson WG. What are placebos, IFFGD 2002; Fact Sheet No. 172)

Postprandial

After meals.

Prebiotics

Nondigestible food ingredients that beneficially affect the host by selectively stimulating the growth and/or activity of one or a limited number of microbes already resident in the gut microbiota.

Precursor

A substance, cell or component from which another is formed.

Prevalence

The proportion of people in the entire population who are found to be with a disease or disorder at a certain point in time (sometimes called a "cross section"), without regard to when they first got the disease.

Primary care

First contact medical care to patients.

Primary care physician

A doctor who manages a person's health care over time. A primary care doctor is able to give a wide range of care, including prevention and treatment, and can refer a patient to a specialist.

Primary lactase deficiency

When a person is born with the inability to digest lactose, a sugar found in milk and milk products. Lactose can't be digested because there is not enough of an enzyme, called lactase, in the body. Consuming milk and dairy products causes diarrhea, bloating, gas, and discomfort. This deficiency can also develop over time, as the amount of lactase in the body decreases with age.

Probiotics

Microbial cell preparations or components of microbial cells that have a beneficial effect on the health and well being of the host. The World Health Organization defines probiotics as live microorganisms that can provide benefits to human health when administered in adequate amounts.

Proceedings

A collection of current research reports, usually presented as brief abstracts, from a scientific meeting.

Progressive muscle relaxation

Voluntary relaxation through systematic tensing and relaxing of different muscle groups.

Prokinetic

Drugs that enhance propulsion of contents through the gut.

Prospective study

A study that utilizes carefully defined protocols to determine an outcome that is unknown beforehand.

Protease

A protein that digests other proteins.

Protein

A large complex molecule made up of one or more chains of amino acids. Proteins perform a wide variety of activities in the cell.

Protocol

An action plan for a clinical trial. The plan states what the study will do, how, and why. It explains how many people will be in it, who is eligible to participate, what study agents or other interventions they will be given, what tests they will receive and how often, and what information will be gathered.

Proton pump inhibitor (PPI)

A drug that limits acid secretion in the stomach.

Pseudo-obstruction (intestinal)

A motility disorder with symptoms like those of a bowel blockage, but with no physical evidence of blockage or obstruction. Symptoms may include cramps, stomach pain, nausea, vomiting, bloating, fewer bowel movements than usual, and loose stools. May be chronic or acute (Ogilvie's syndrome).

Q

R

Radiation proctitis

Bleeding, mucous and bloody discharge, spasm of the rectal wall, urgency, and incontinence due radiation-induced damage to the rectum. Late symptoms result from scarring of the rectal and anal muscles with loss of some of the small blood vessels. The rectum becomes stiff and noncompliant (nonstretchable) and abnormal blood vessels may develop.

Random allocation

A method where all participants in a study have the same chance of being assigned to a study group, rather than allocation being assigned by the investigators.

Randomized controlled trial

A study in which people are allocated at random to receive one of several clinical interventions. One intervention is regarded as a standard of comparison or control.

Receptor

A structure in each cell that selectively receives and binds a specific substance, such as a neurotransmitter.

Rectum

The lower end of the large intestine, leading to the anus.

Refractory

Resistant to treatment.

Resection, intestinal

The surgical removal of a diseased portion of the intestines.

Retrospective study

A study in which known outcomes are examined in hindsight using existing records. A retrospective study is usually less reliable than a prospective study.

Reuptake

A process in which chemical neurotransmitters, after transmitting their message, are taken up again by nerve endings, broken down, and inactivated.

RNA

Abbreviation for ribonucleic acid, the molecule that carries out DNA's instructions for making proteins.

Rome Criteria

Lists of symptoms and criteria generally agreed upon by experts to diagnosis a functional gastrointestinal disorder.

S

The current set of peer-evaluated consensus models about how natural phenomena work, which often differ between groups of researchers at the research frontier.

Scientific progress

The cumulative growth of a system of knowledge over time, in which useful features are retained and nonuseful features are abandoned, based on the rejection or confirmation of testable knowledge.

Scintigraphy

An imaging method in which a mild dose of a radioactive substance is swallowed to show how material moves through the GI tract.

Sensitivity (diagnostic)

The ability of a test to correctly identify a disease or condition (positive test result) when it is present.

Sensitization

Enhancement of a response by an organism that is produced by delivering a strong, generally noxious, stimulus. A neuron becomes more excitable or responsive; it may respond more intensely to naturally occurring stimuli, either peripherally (in the viscera) or centrally (in the brain).

Serotonin (5-hydroxytryptamine, or 5-HT)

A chemical neurotransmitter (a chemical that acts on the nervous system to help transmit messages along the nervous system). It is found in the intestinal wall and the central nervous system. More than 90% of the serotonin in the body resides in the gut.

Short bowel syndrome (short gut)

A condition in which nutrients are not properly absorbed because a large part of the small intestine is missing or not functioning properly.

Sigmoid colon

The S-shaped section of the colon that connects to the rectum.

Sigmoidoscopy

Examination of the inside of the sigmoid colon and rectum using an endoscope -- a thin, lighted tube (sigmoidoscope). Samples of tissue or cells may be collected for examination under a microscope. Also called proctosigmoidoscopy.

Significant or statistically significant

A statistical term indicating that the results of a study are stronger than would be expected from chance alone.

Skin test

A test for an immune response to a compound by placing it on or under the skin.

Small intestine

The part of the digestive tract that is located between the stomach and the large intestine.

The ability of a test to correctly classify an individual as not having a disease or condition (negative test result) when it is absent.

Sphincter

Ring of muscle that opens and closes.

Sphincter of Oddi

A muscle at that juncture of the bile and pancreatic ducts and the small intestine. It functions by opening and closing these ducts.

Sphincter of Oddi Dysfunction

An abnormality of the contractions of the sphincter of Oddi, which may be seen with a biliary and/or pancreatic type of pain in the upper right and middle parts of the abdomen (below the breastbone). It most commonly occurs in middle-aged women who have had their gallbladder removed. Treatment may involve surgery or medicines aimed at decreasing resistance to the flow of bile or pancreatic juice caused by the sphincter dysfunction.

Spinal cord

A column of nerve tissue that runs from the base of the skull down the back. It is surrounded by three protective membranes, and is enclosed within the vertebrae (back bones). The spinal cord and the brain make up the central nervous system, and spinal cord nerves carry most messages between the brain and the rest of the body.

Squamous cell

A flat cell that looks like a fish scale under a microscope. Squamous cells cover internal and external surfaces of the body.

Stress

The neurophysiological and subjective response to stimuli. In contrast to the common interpretation of the term "stress" as a psychological phenomenon, it should be understood as any real or perceived perturbation of an organism's homeostasis, or state of harmony or balance. Stress may disrupt the function of nerve and even immune cells in the GI tract and in the brain. The central stress system involves the release of chemical stress mediators in the brain, which in turn orchestrate an integrated autonomic, behavioral, neuroendocrine, and pain modulatory response. This biological response in turn will alter the way the brain and the viscera (internal organs such as the gut/intestines) interact, and this altered brain-gut interaction can result in worsening of symptoms in functional GI disorders. For example, stress can increase GI symptoms by changing how the brain controls unwanted and painful sensation.

Stressor

Internal or external factors or stimuli that produce stress. They can be physical, biological, environmental, or psychological; each can activate central stress circuits in an individual. For example, worry about the untimely and unpredictable onsets of uncontrollable abdominal pain or an uncontrollable bowel movement qualify as stressors sufficient to activate the central stress system.

Stricture

Abnormal narrowing of a body opening.

Synapse

The point between two nerve cells (neurons), across which chemical neurotransmitters carry messages.

Syndrome

A set of symptoms or conditions that occur together and suggest the presence of a certain disease or an increased chance of developing the disease.

V

A nerve that extends from the brain to the abdomen, important in regulating functions of the viscera. Signals on the vagus nerve travel from the brain to the gut and from the gut to the brain.

Validity

The extent to which a measure accurately reflects the concept that it is intended to measure.

Valsalva maneuver

Voluntary increasing pressure in the abdominal cavity with the diaphragm and abdominal muscles to bear down on the rectum to facilitate defecation.

Villi

Tiny finger-like projections on the surface of the small intestine that help absorb nutrients.

Viscera

Internal organs such as the gut/intestines or bladder.

Visceral

Relating to the internal organs, such as the gut/intestines or bladder.

Visceral hypersensitivity (intestinal)

Enhanced perception, or enhanced responsiveness within the gut — even to normal events.

Z

Zollinger-Ellison syndrome (ZES)

A rare disorder that causes tumors in the pancreas and duodenum. The tumors secrete a hormone called gastrin that causes the stomach to produce too much acid, which in turn causes stomach and duodenal ulcers (peptic ulcers).